
#float {
    width: 400px;
    height: 400px;
    background-color: mediumaquamarine;
    float: right;
}
#float2 {
    width: 400px;
    height: 400px;
    background-color: aqua;
    float: left;
    margin: 0 40px;
    clear: both;
    overflow: hidden;
}
#float3::after {
    width: 400px;
    height: 400px;
    background-color: aquamarine;
    display: inline-block;
    float: right;
}